The car rental companies make you drop off your car on one side, and pick up another car on the south island. They require 72 hours notice to arrange the car on the other side. Usually this is a very smooth process, with offices right at the terminal on both sides, but what made it more complicated for us was that we had rented an infant car seat, and needed one on the other side. We were told 2 days before we travelled on the ferry that we would need to take the car seat WITH us on the ferry, and that they would install it for us on the other side. So, not only would we have to carry our luggage, stroller, and baby, we would also need to bring the car seat with us! Fortunately, the way that luggage works is pretty straightforward – it’s sort of like an airline – we just dropped it off on one side and it appeared on the conveyor belt at the other side, with luggage trolleys in case you need one. The Avis agent in Wellington took great care of us, and made sure that the process was smooth – she was really nice, and helped us carry the car seat to checkin. The car seat did not get dirty on the ferry. Once we got our new car in Picton, the gentleman who tried to install it rear-facing , despite never having done it before, did a great job and it ended being much more secure than it was when installed at the airport in Auckland.The ferry itself was very comfortable. We found seats right by the children’s play area, with toys and tunnels for our daughter to climb through. There was even a nursery, with 4 bunk bed cribs for children to take naps in, a clean changing station, a bottle warmer, and a nursing chair. There was a freshly cleaned wall size chalkboard for children to write on. There was a big LCD tv up on the wall with foam seating The food in the cafeteria on the boat was reasonably priced and surprisingly good. The views from the top deck were beautiful.